Yocheved Ben-Bassat

Skeletal and functional effects of treatment for unilateral posterior crossbite

Unilateral posterior crossbite (UPXB) is a common malocclusion, frequently presenting a lower midline deviation, accompanied by Class II subdivision relationships in final closure and a very high prevalence of the reverse sequencing (RS) pattern of jaw movement. These features often persist even after the elimination of the crossbite. The purpose of the present study was to examine in detail the morphologic, skeletal, and functional effects of the treatment for this malocclusion category. The experimental group consisted of 24 children in the mixed dentition stage with UPXB who were treated with removable expansion plates and a control group of 10 age-matched children with normal occlusion. Longitudinal follow-up revealed a stable dental maxillary arch expansion of at least 1.5 mm but a complete elimination of crossbite in only 50% of the cases. The frequent persistence of Class II subdivision relations and lower midline deviation that were not due to functional mandibular shift was striking. The pretreatment posteroanterior (P-A) cephalograms indicated reduced facial and maxillary widths. After treatment, the achieved maxillary width increase was greater than expected with normal growth. Longitudinal assessment of the mandibular movement response revealed by the electrognathograph showed a high prevalence of RS, which was reduced after treatment. In conclusion, (1) a higher than expected prevalence of skeletal transverse aberrations at the maxillary and zygomatic levels were found in the UPXB group; (2) the removable expansion appliance induces transverse growth of the maxilla; and (3) an inherent pattern of jaw movement is characteristic to the UPXB and does not change significantly with orthodontic treatment.

Skeletodental patterns in patients with multiple congenitally missing teeth.

Congenitally missing teeth (CMT) are a relatively frequent phenomenon. In severe cases of multiple CMT, the skeletodental pattern can be unique. However, the characteristics of this pattern are still controversial. Thus, it was our aim to evaluate the skeletodental patterns of patients with multiple CMT and compare them with norms. Lateral cephalograms of 115 subjects with at least 3 CMT, of at least 2 different tooth groups (excluding third molars), were analyzed. The measurements were compared with classical and Israeli norms. Differentiation between anterior and posterior lack of teeth was also evaluated. In the CMT patients, the maxillary and mandibular basal bones were more retruded than in normal populations, but the intermaxillary relationship was normal. The profile was flatter than in the normal Israeli population but more convex than the classical norms. In the vertical dimension, the study group exhibited a reduced Frankfort mandibular plane angle when compared with Israeli norms. The dental pattern was characterized by upright incisors. When differentiation between anterior and posterior lack of teeth was undertaken, the above features were exacerbated in the patients with anterior tooth absence. It was concluded that patients with multiple CMT demonstrate a characteristic skeletodental pattern, especially those with missing incisors.

Skeletal and dental patterns in patients with severe congenital absence of teeth

INTRODUCTION Children with severe congenital absence of teeth present uncommon morphologies and therapeutic challenges. This study was designed to investigate the characteristic skeletal and dental features of this group. METHODS A group of 28 children with at least 10 congenitally missing teeth (excluding third molars) was examined roentgenographically. The data were collected from their intraoral series or panoramic views and lateral cephalograms. The results of their cephalometric analyses were compared with classic cephalometric norms and with local population norms. RESULTS Specific patterns of incisor, premolar, and third molar absence emerged. The cephalometric parameters of the children with severe absence differed from the classic norms in bimaxillary retrognathism, chin angle, and maxillary incisor inclination. These children differed from the Israeli norms in almost all parameters examined. CONCLUSIONS Patients with severe congenital absence of teeth have unique dental and skeletal patterns.

Does a secular trend exist in the distribution of occlusal patterns

The existence of a secular trend in the distribution of occlusal patterns was studied in two generations of children. Study models and demographic data of a sample of 265 children from the previous generation (group A) and recordings of clinical examinations of 988 children from the present generation (group B) served as the data base for this study. Children in whom caries affected the occlusion and those in the deciduous dentition stage were excluded. Thus, occlusal analysis was performed for 102 children in group A and 703 in group B. A dramatic decrease was found in the prevalence of caries affecting the occlusion. No difference existed between the two groups with respect to molar and canine anteroposterior relationships. However, there was a decrease in the prevalence of normal occlusion accompanied by an increase of Class I malocclusion.

Cephalometric pattern of Jewish East European adolescents with clinically acceptable occlusion

Knowledge of the normal dentofacial patterns of various ethnic groups is important for clinical and research purposes. The objective of this study was to describe the dentofacial pattern of one Jewish ethnic group and to compare it with accepted standards for other white populations. Lateral cephalometric radiographs of 18 children of Jewish East European origin with clinically acceptable permanent occlusion, ages 11 to 13 years, were used. A computer-aided cephalometric analysis was performed, and the mean values and standard deviations for the various cephalometric variables were obtained. When compared with some classical standards, it was found that this ethnic group tended toward a mild skeletal Class II, a convex profile, and a more vertical direction of growth. These features appeared in persons selected on the basis of a clinically acceptable occlusion, suggesting the existence of dental compensations. Understanding these natural accommodations of the dentition to skeletal variations can be clinically useful when establishing treatment goals.

Prevalence of dental features that indicate a need for early orthodontic treatment

The aim of the study was to establish the prevalence of dental features that indicate a need for early orthodontic treatment (EOT). A group of schoolchildren in the mixed dentition stage (7-11 years old) (n = 432) was clinically screened for indications for EOT. Over 1/3 of the youngsters (34.7 per cent) presented at least one of the indications for EOT: anterior and posterior crossbites (including edge to edge occlusion) were found in 9.5 and 23.3 per cent, respectively; Angle Class III was found in 3 per cent; increased overjet (≥7 mm) prevailed in 3.7 per cent and was significantly related to risk for dental trauma (P = 0.001); while oral habits were practiced by 10.9 per cent, open bite was found only in 6.5 per cent, both predominantly among girls (P = 0.006 and P = 0.012, respectively); impinging overbite was present in 5.2 per cent, mainly in boys (P = 0.006); crowding >5 mm was found in 6.9 per cent for the maxilla and in 6 per cent for the mandible. Loss of tooth material affecting tooth position was found in 15.3 per cent. Normal occlusal relationships were found in 10.9 per cent only. The findings indicate that almost 1/3 of the examined children in the mixed dentition stage require EOT. Sexual dimorphism was demonstrated for several occlusal features.

Periodontal Status of Impacted Maxillary Incisors Uncovered by 2 Different Surgical Techniques

PURPOSE The aim of this retrospective study was to compare the postretention clinical appearance and the pulpal and periodontal status of surgically exposed and orthodontically aligned impacted maxillary central incisors, treated by 2 different surgical techniques-open eruption (OE) versus closed eruption (CE). PATIENTS AND METHODS The OE group consisted of 11 patients, age 15 to 38 years. The 11 patients in the CE sample (aged 14-28 years) were selected from a larger group of patients treated by this method, by carefully matching them to the patients in the OE group, in terms of cause and height of impaction. The length of the follow-up period was comparable for both groups (median of 9 years for the CE group and 10 years for the OE group). The clinical and radiographic variables were compared by paired t and chi(2) tests. RESULTS The only parameters where statistically significant differences between the 2 study groups were found were crown length and bone support; that is, the central incisors uncovered by the OE technique had longer clinical crowns (by a mean of 1.37 mm) and decreased bone support (7.5% less on the mesial side) compared with those treated with the CE technique. Pulp changes with crown discoloration were only seen in the trauma-related group, independent of surgical technique. CONCLUSIONS The choice of surgical technique in the exposure of impacted central incisors has important implications in the success of the orthodontic treatment of impacted incisors, in the long term, in relation to periodontal support and to appearance.

Buccal ectopia of maxillary canines with no crowding

INTRODUCTION Buccally displaced canines (BDC) are usually found in crowded dentitions. Nevertheless, a small but significant number of patients with BDC have no crowding. In this study, we compared BDC dentitions with no crowding (BDC-nc), BDC dentitions with crowding (BDC-c), and uncrowded dentitions with normally erupted canines (C). METHODS The mesiodistal (MD) widths of maxillary permanent teeth, the prevalence of maxillary lateral incisor anomalies, and the dental age were compared in BDC-nc (n = 30; 17 male, 13 female), BDC-c (n = 41; 21 male, 20 female), and C dentitions (n = 40; 20 male, 20 female). RESULTS No differences in the MD dimensions of the teeth in the BDC-nc and C subjects were found; teeth in the BDC-c group were slightly larger. Only the lateral incisor was consistently smaller in the BDC-nc group. The prevalence of lateral incisor anomalies was markedly increased in the BDC-nc (28.3%) compared with the BDC-c (7.6%) and the C (8.6%) groups. No discrepancies were found in dental age. CONCLUSIONS These findings suggest that, in addition to a genetically based etiology, buccal displacement in BDC-nc subjects might also be the result of lack of guidance from an adjacent anomalous lateral incisor.

Maturation of teeth adjacent to dental agenesis site

Abstract Objective. The purpose of this study was to evaluate the developmental stage of teeth adjacent to the agenesis site in comparison to their antimeres. Materials and methods. Panoramic views of 39 patients with unilateral dental agenesis and 42 normal controls were evaluated. The dental developmental stage (normal or delayed) of the teeth adjacent to the agenesis site was determined for each patient using the Haavikkos method, while the overall dental age was determined by Beckers method. Results. No statistically significant difference was found in the developmental stage of teeth adjacent to the agenesis, compared to their antimere and to the same teeth in the normal control group. However, the prevalence of cases with no difference in development was almost double for the tooth distal to the agenesis site compared to the tooth mesial to the agenesis site in the hypodontia group (84.6% distal and 43.6% mesial; p < 0.001) and in the control group (83.3% distal and 52.4% mesial; p < 0.002). In most of the cases the tooth distal to the agenesis site was the 1st permanent molar. Conclusions. (1) No difference was found between the developmental stage of teeth adjacent to the agenesis site and their antimeres. (2) Teeth mesial to the agenesis site showed some delay in development compared to teeth distal to the agenesis site, in this study. (3) The 1st molars, which were in most of the cases the distal adjacent tooth to the site of agenesis, showed developmental stability. (4) Additional longitudinal studies are needed to examine the dental developmental pattern in patients with agenesis.